In Louisiana, candidates have until Aug. 22 to file the necessary paperwork for a bid, and all candidates who qualify for the ballot run on Election Day in November. If no candidate receives a majority of the vote, the race kicks to a runoff in December between the two top vote recipients.

"There's no doubt I've fallen short and I'm asking for forgiveness," McAllister said in a statement. "I'm asking for forgiveness from God, my wife, my kids, my staff, and my constituents who elected me to serve. Trust is something I know has to be earned whether your a husband, a father, or a congressman. I promise to do everything I can to earn back the trust of everyone I've disappointed."

Candidates listed as potential challengers in the immediate aftermath of the scandal include many of the Republicans who ran in the special election this past fall, including:

State Sen. Neil Riser, the Republican who lost to McAllister in the special election runoff. GOP operatives at the time said Riser was the heir apparent to the seat, which came open when former Rep. Rodney Alexander resigned to take a job in Louisiana Gov. Bobby Jindal's administration.

Former Rep. Clyde Holloway, who served in Louisiana's then 8th District from 1987 to 1993. Holloway ran in the recent special election and came in fourth behind Riser, McAllister and Democrat Jamie Mayo.

State Rep. Jay Morris, a Republican state legislator who ended in sixth place in the special election.

GOP operatives added that Adam Terry, McAllister's current chief of staff, could also look to run. Terry considered jumping into the special election last year, but decided against a bid.

Republicans say Mayo, too, could run again in November. Mayo, who serves as mayor of Monroe, La., came in third in the special election this fall, behind McAllister and Riser.

While the scandal is still unfolding, GOP operatives said McAllister would likely be vulnerable in November.

Bernie Pinsonat, a longtime Louisiana pollster, said that many Lousiana pols have survived scandal in the past, including Republican Sen. David Vitter, who faced scandal when his phone number was included in the high-profile "D.C. Madam" prostitution scandal in 2007.

But Pinsonat added that the video of McAllister's affair makes this case different.

"I don’t know of any time that we've had a video to accompany it, so even for Louisiana standards this is uncharted waters," Pinsonat said.